PROJECT SUMMARY/ABSTRACT Kidney transplant is regarded as the best treatment modality for end-stage renal disease (ESRD). Despite the known benefits of kidney transplantation over dialysis, inequities in access to transplantation are present by sex. In both adults and children, female sex is associated with a lower likelihood of receiving a kidney transplant compared to male sex. The reasons for these disparities in access to transplant among women versus men are unclear. Because of the unique characteristics of populations with different underlying cause of ESRD, it is possible that sex-based disparities in access to transplant differ among the different underlying attributed causes of ESRD. Characteristics specific to different causes of ESRD (such as the propensity for a disease to progress more rapidly in one sex and therefore preclude completion of the transplant evaluation process prior to dialysis) may lead to differences in the magnitude of the inequities in access to transplant among men versus women. In addition, prior literature has also shown that women are less likely to receive a living donor transplant (especially from spouses), even though women are more likely to donate a kidney. The decision not to donate a kidney despite eligibility for donation may be associated with a potential donors' subjective perceptions regarding their own health and donor candidacy. We hypothesize that these health perceptions may differ among male versus female donors, contribute to lower donation rates by men, which in turn, lead to a smaller pool of potential donors that lowers access to kidney transplantation among women. The Kidney Failure Risk Projection (KFRP) equation has recently been established to provide objective estimates of the 15-year risk for the development of ESRD among potential donors. In this study, we will determine whether there are differences in male versus female donors' perception of self-health, and we will compare these self-perceptions with the objective measure of the risk of ESRD using the KFRP equation. The objectives of this proposal are to 1) determine whether differences in access to transplantation by sex are modified by underlying cause of ESRD and 2) understand perceived versus actual medical barriers to living kidney donation according to donor sex. The expected outcome of this proposal is that we will enhance our understanding of whether subpopulations of patients with various underlying causes of renal disease may benefit from specific interventions to equalize parity in transplant. We also seek to understand which factors may be modifiable in the living donor evaluation process to improve living donor transplantation rates and access of women to living donor transplants. UCSF is well-suited for the conduct of this proposal, given that UCSF is one of the largest transplant centers in the United States, performing 300-350 kidney transplants (including about 150 living donor transplants) annually.